airline inventory

Even as most flights are packed these days, some planes still take off with plenty of vacant seats, including in First and Business Class, effectively losing the airlines hundreds of thousands of dollars. Offering lower last-minute fares on undersold flights seems a logical solution, and carriers do it sometimes, but those attempts are utterly insufficient.

Let’s look at a recent international flight — most U.S. airlines give away free upgrades on domestic routes to fill their premium cabins. I picked a United Airlines flight on a route with traditionally heavy demand in Business Class: San Francisco to Sydney. As the above image shows, on June 19, that Boeing 747 left with 18 empty seats in Business Class, including on the upper deck.

The lowest Business Class fare on United on that route is — and has been for some time — about $6,400, which requires a 50-day advance purchase. If bought at least 21 days before departure, a ticket costs about $9,800, and about $12,300 at least three days in advance. The lowest last-minute fare is about $12,800. You do the math to figure out how much money United lost as a result of those 18 unsold seats…

There have been hundreds of media stories in the last week about the Delta Airlines website “glitch” that overcharged members of its loyalty program on airfare across the board, but what none of those stories tells us is how to recognize and fight such airline practices — whether deliberate or accidental.

As this column has pointed out before, airlines try to overcharge customers all the time, and a decade ago, I used to fall for some of those tricks. That’s why I decided to learn the system — and that’s one of the reasons I wrote “Decoding Air Travel.” If you ever needed proof that knowledge means power, look no farther.

So how could you have known that the Delta website was charging you more than the lowest available fare? First, you have to understand what an airline tariff is: A list of all published base fares on a certain route, along with their rules and permitted routing — they carry a code corresponding to a letter of the alphabet. The second thing is the flight inventory, or the number of seats in each booking class made available on a certain flight…

I’ve always brushed off suggestions that airline websites are deliberately programmed to increase the fare if you don’t take their initial offer immediately. But I’ve become suspicious since Air Canada’s site recently jacked up a ticket price on me by hundreds of dollars in seconds, even as its lowest published fare and the flight inventory remained unchanged.

Airlines have gone to great lengths in recent years to encourage customers to book tickets on their websites, and that can certainly save travelers time and hassle in the event of any changes to a ticketed reservation. However, to their utter shame, many carriers haven’t built reliable and user-friendly sites. In fact, some airlines, such as South Korea’s Asiana, have outsourced their entire online booking process — at least in the U.S. market — to a third-party travel agency, which charges its own booking fees…